Adult T-cell leukemia (ATL) is a malignant tumor caused by infection with HTLV-1. It is estimated that the number of carriers of HTLV-1 is about 1.2 millions in Japan and 10 to 20 millions in the world, and believed that 2 to 5% of them develop ATL in their lives. The survival rate after the onset of ATL is extremely low, and although a multidrug therapy using various anticancer drugs has been conducted as a treatment, the treatment outcome is poor due to rapid acquisition of drug resistance.
As a conventional therapeutic drug for adult T-cell leukemia, for example, Patent Literature 1 discloses a therapeutic agent containing fucoxanthin or fucoxanthinol as an active ingredient. Further, Patent Literature 2 discloses a therapeutic agent for adult T-cell leukemia containing digitoxin as an active ingredient.
Under such circumstances, development of a new agent having specificity to an ATL cell has been demanded.